1Thinly slice four onions and add them to a slow cooker along with brown sugar, butter, Worcestershire sauce, and two garlic cloves. Stir and set on low overnight.
2In the morning, add one tablespoon of flour to the caramelized onions and stir to combine.
3Add one bottle of beer (pumpkin beer is used in the video), two cartons of beef broth, two sprigs of fresh thyme, two bay leaves, a pinch of salt, and a pinch of black pepper.
4Stir everything together, cover, and cook on high for 2–4 hours or on low for 6–8 hours.
5While the soup simmers, make the cheesy French toast. Cut a loaf of French bread into slices. In a bowl, whisk together eggs, milk, salt, pepper, and parmesan cheese.
6Dip each slice of French bread into the egg mixture, and cook in a hot skillet with butter on both sides for 3–4 minutes until golden brown.
7Ladle the soup into oven-safe ramekins, top with the cheesy French toast, and sprinkle with shredded gruyere cheese.
8Bake under the broiler until the cheese is melted, bubbly, and browned.